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Old 27th April 2014, 06:44 PM   #21
gugi100 is offline gugi100  Netherlands
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Hi Ales,

Is it possible to make an extra "I" (Vin) connection in the trace from I to C15 (position near C3) and a GND connection next to it?

In this way it easier to connect to a board with only GND V+ entrance. Since you van supply Vin en GND easy through the extra Vin and GND.

Gr GJ
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Old 28th April 2014, 02:41 PM   #22
mravlca is offline mravlca  Slovenia
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Quote:
Originally Posted by rhythmsandy View Post
can the input and output caps be tantalum KEMET make?
Generally its said Tantalums are better than ceramics or may be equivalent to ceramic
Invalid Request
Sure ceramic capacitors can replaced with tantalum, but it is better to measure what kind of difference do you achieve with this action.

Quote:
Originally Posted by gugi100 View Post
Hi Ales,

Is it possible to make an extra "I" (Vin) connection in the trace from I to C15 (position near C3) and a GND connection next to it?

In this way it easier to connect to a board with only GND V+ entrance. Since you van supply Vin en GND easy through the extra Vin and GND.

Gr GJ
Actually this is already realized, only downside is that then S- doesn't have any function.

I ordered some 3pin regulator PCBs and I'll see how they perform.


Best Regards,
Ales
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Old 2nd August 2014, 12:37 PM   #23
mravlca is offline mravlca  Slovenia
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Hi guys,

it has been a while since I did something on this PCB. Those 3pin regulators turned out bad, since I made too small package for TPS7A4700, so all PCBs ended up in trash.
Now I have a design that uses two TPS7A4700/1, so with two PCBs you can get 3.3V, 5V and also symmetrical +/-12V voltage outputs (these voltages are for example, other values can also be configured). As you can see there is sense pin for each voltage output, but if one is not planing to use it can be shortened to output via solder jumper. I need to make a few more checks, then gerbers are going to fab.

BR,
Ales
Attached Images
File Type: jpg TPS7A4700.JPG (176.7 KB, 305 views)
File Type: jpg TPS7A4700_scheme.JPG (95.5 KB, 302 views)
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Old 2nd August 2014, 02:24 PM   #24
Can you say Audio?
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Still very interested mate Layout looks good. Have you made provisions for a heatsink(s) on the bottom?
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Old 3rd August 2014, 04:10 AM   #25
rol is offline rol
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Interested in a couple of boards, but why do we need 2 boards in order to get +/- 12v?
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Old 3rd August 2014, 06:36 AM   #26
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Interesting boards,
A few ideas... Better to make pcb with diodes or bridge in upper side of a pcb. Because if it is underside, it is not possible to use 3 or 4mm termal rubber and install it directly to the bottom wich can be used as a termal heatsink.
Can you do it in that way that can be breakable in 1 or 2 regulator...not as
2 pcs reg in one board.
For negative voltage did you mean TPS7A47... or TPS7A33..?
Can you do for output caps also for bigger dimension or just bigger gnd pads. Because pps caps or poscaps are not in small dimensions.
Like C1 and C2 ore maybe a little further. C2 and C3 are too close.
Maybe one smd led and resistor ath the output.
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Old 3rd August 2014, 10:32 AM   #27
mravlca is offline mravlca  Slovenia
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Quote:
Originally Posted by MisterRogers View Post
Still very interested mate Layout looks good. Have you made provisions for a heatsink(s) on the bottom?
The board is designed so that the heatsink can be mounted on the bottom.

Quote:
Originally Posted by rol View Post
Interested in a couple of boards, but why do we need 2 boards in order to get +/- 12v?
Because regulators are single output we need two of them to get symmetrical output. One PCB has two almost identical circuits.

Quote:
Originally Posted by androa76 View Post
Interesting boards,
A few ideas... Better to make pcb with diodes or bridge in upper side of a pcb. Because if it is underside, it is not possible to use 3 or 4mm termal rubber and install it directly to the bottom wich can be used as a termal heatsink.
I was also thinking about this option

Quote:
Originally Posted by androa76 View Post
Can you do it in that way that can be breakable in 1 or 2 regulator...not as
2 pcs reg in one board.
Noted. Though I still have to source cheap PCB manufacturer that offers this function.

Quote:
Originally Posted by androa76 View Post
For negative voltage did you mean TPS7A47... or TPS7A33..?
For negative symmetrical output I mean to use TPS7A47, using this device makes sense to make PCB breakable.
Quote:
Originally Posted by androa76 View Post
Can you do for output caps also for bigger dimension or just bigger gnd pads. Because pps caps or poscaps are not in small dimensions.
I can do bigger GND pad on the other side of output line. But I don't know how PPS or POScaps would perform on the output, also maximum capacitance for PPS is 1uF (as I could found) and we need here 50uF. According to EVM they use here X5R capacitors.

Quote:
Originally Posted by androa76 View Post
Like C1 and C2 ore maybe a little further. C2 and C3 are too close.
Maybe one smd led and resistor ath the output.
Hope I will manage to squeeze all in.

Best Regards,
Ales
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Old 3rd August 2014, 12:52 PM   #28
mravlca is offline mravlca  Slovenia
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So this is what I came up with in couple of hours now. Instead of making breakable PCB I decided to make also single output PCB. This is because I will need symmetrical PSU for powering line drive from minidsp and single PSU for powering minidsp itself.
I also got the idea that single PCB could get daughter board with power transistor to get more current but I don't know how much would I degrade regulator specs.

BR,
Ales
Attached Images
File Type: jpg TPS7A4700_single_PCB.JPG (95.5 KB, 250 views)
File Type: jpg TPS7A4700_symmetrical_PCB.JPG (154.4 KB, 249 views)
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Old 3rd August 2014, 01:09 PM   #29
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Quote:
Originally Posted by mravlca View Post
So this is what I came up with in couple of hours now. Instead of making breakable PCB I decided to make also single output PCB. This is because I will need symmetrical PSU for powering line drive from minidsp and single PSU for powering minidsp itself.
I also got the idea that single PCB could get daughter board with power transistor to get more current but I don't know how much would I degrade regulator specs.

BR,
Ales
I believe you are using this pcb with dual secondary transformer with same voltage.

I generally have doubt about this Regulator is it stable? I am about to order 20 units of it for my DACs and Preamps hence a bit doubtful about this little chip.

Options:

1. Can I use single 47uf MLCC at the output? instead of 5 x 10uf MLCC?

2. I have fixed value requirement like 3.3V or 5V or 7V so can I use a super miniaturized pcb? all very close?

3. Im planning to use Metal film through hole resistors instead of surface mount as through hole resistors give less shot noise than the smd resistors.
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Old 3rd August 2014, 02:55 PM   #30
mravlca is offline mravlca  Slovenia
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Quote:
Originally Posted by rhythmsandy View Post
I believe you are using this pcb with dual secondary transformer with same voltage.

I generally have doubt about this Regulator is it stable? I am about to order 20 units of it for my DACs and Preamps hence a bit doubtful about this little chip.

Options:

1. Can I use single 47uf MLCC at the output? instead of 5 x 10uf MLCC?

2. I have fixed value requirement like 3.3V or 5V or 7V so can I use a super miniaturized pcb? all very close?

3. Im planning to use Metal film through hole resistors instead of surface mount as through hole resistors give less shot noise than the smd resistors.
As I haven't built any of this regulators I can't say if there are any stability issues.

1. Yes you can.

2. It is recommended that all the components are as close as possible to the chip. I have also seen designs where multiple TPS7A4700 are close to each other.

3. Interesting feature of this regulator is that it does not use external resistors. On my circuit there is only one resistor per regulator and that is for LED.

BR,
Ales
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